Salvaged robot arm makes a big 3d printer

Wow, building a precision 3d printer is amazingly easy if you can get your hands on an industrial-quality robot arm. [Dane] wrote in to tell us about this huge extruder printer made from an ’80s-era SCARA robot arm. It is capable of printing objects as large as 25″x12″x6.5″.

This 190 pound beast was acquired during a lab clean out. It was mechanically intact, but missing all of the control hardware. Building controllers was a bit of a challenge since the it’s designed with servo motors and precision feedback sensors. This is different from modern 3d printers which use stepper motors and no feedback sensors. A working controller was built up one component at a time, with a heated bed added to the mix to help prevent warping with large builds. We love the Frankenstein look of the controller hardware, which was mounted hodge-podge as each new module was brought online.

You can see some printing action in the clip after the break. A Linux box takes a design and spits out control instructions to the hardware.

@ elbow direction:
I haven’t actually solved that part yet in the kinematic model, it ends up working but VIOLENTLY jerking between ‘left’ and ‘right’ forward models. i mitigated it by placing a max-acceleration in that mode, but i’m always open to a more elegant solution.

I may have the source code for that still. It probably got purged during a hard drive swap somewhere along the line. It took a lot of effort to get that one code block to work and we shared it among each other after someone got it working well.